Phospholipids from the free-living nematodeCaenorhabditis elegans

The phospholipid and the fatty chain compositions of diacyl, alkylacyl and alkenylacyl glycerophospholipids of the free-living nematode,Caenorhabditis elegans, were investigated. The phospholipids were comprised of 54.5% ethanolamine glycerophospholipid (EGP), 32.3% choline glycerophospholipid (CGP), 8.1% sphingomyelin and 5.1% others. The most abundant fatty acid in CGP was eicosapentaenoic acid (20∶5n−3). The fatty acids in CGP were more unsaturated than those in EGP. Alkenylacyl and alkylacyl subclasses accounted for 1.0 and 2.6%, respectively, of CGP and 14.0 and 19.6%, respectively, of EGP. At least 80% of the alkenyl and alkyl groups were 18∶0 chains and the remaining were odd numbered chains. The potential presence of platelet-activating factor (PAF) was examined by bioassay, but PAF-like activity was not detected in the extracts of this nematode.     

Sterol metabolism in the nematodeCaenorhabditis elegans

The metabolism of various dietary sterols and the effects of an azasteroid on sitosterol metabolism in the free-living nematodeCaenorhabditis elegans was investigated. The major unesterified sterols ofC. elegans in media supplemented with sitosterol, cholesterol or desmosterol included 7-dehydrocholesterol (66.5%, 40.5%, 31.2%, respectively), cholesterol (6.7%, 52.3%, 26.9%), lathosterol (4.4%, 3.6%, 1.7%) and 4α-methylcholest-8(14)-en-3β-ol (4.2%, 2.1%, 3.8%). Esterified sterols, representing less than 20% of the total sterols, were somewhat similar except for a significantly higher relative content of 4α-methylcholest-8(14)-en-3β-ol (23.3%, 23.4%, 10.6%). ThusC. elegans not only removes the substituent at C24 of dietary sitosterol but possesses the unusual ability to produce significant quantities of 4α-methylsterols. WhenC. elegans was propagated in medium supplemented with sitosterol plus 5 μg/ml of 25-azacoprostane hydrochloride, the azasteroid strongly interfered with reproduction and motility ofC. elegans and strongly inhibited the Δ24-sterol reductase enzyme system; excluding sitosterol, the major free sterols of azacoprostane-treatedC. elegans were cholesta-5, 7, 24-trien-3β-ol (47.9%), desmosterol (9.4%), fucosterol (2.1%) and cholesta-7,24-dien-3β-ol (2.0%). These 4 sterols are likely intermediates in the metabolism of sitosterol inC. elegans.     

Threshold chemosensitivity and hypothetical chemoreceptor function of the nematodeCaenorhabditis elegans

The behavioral responses by the nematodeCaenorhabditis elegans to 12 organic compounds was explored using tethered nematode and computer tracking methods. Results indicate that the nematode is attracted to acetone, diethyl ether, isoamyl acetate, isoamyl alcohol, 2,4-pentanedione, andn-propanol. No responses were detected to acetaldehyde, acetylcholine, ethanol, formaldehyde, i-propanol, and valerate. Isoamyl acetate and acetone were found to be the most potent attractants eliciting minimal responses at concentrations near 10^?10 M. The geometry and charge distribution of a single hypothetical receptor that would interact with all the compounds that elicited a response and none of the compounds that failed to elicit a response is explored.     

Video camera-computer tracking of nematodeCaenorhabditis elegans to record behavioral responses

A new method is used to analyze responses to changes in the concentration of two chemical stimuli. Nematodes are allowed to move around on the surface of a thin layer of agar across which a stream of air blows to carry volatile stimuli. Darkfield illumination provides high-contrast images of the worms which are acquired by a video camera and fed to a microcomputer which is programed to simultaneously track and record the movements and changes in direction of as many as 25 animals. The results are reported in real time. The worms respond to an increase in CO₂ concentration by decreasing the number moving and increasing the number of changes of direction. Both responses adapt to steady-state levels in about half a minute. This suggests that they respond by changing the probability of initiating a reversal bout. This observation adds a repellent to the class of stimuli thatC. elegans reponds to by klinokinesis. The resonses to changes in oxygen concentration are somewhat different. Movements and changes in direction both decrease when the oxygen concentration falls and increase when the concentration rises. No adaptation is seen within the one-minute time span observed. This observation provides further evidence that the response to oxygen differs from the response to other chemicals and may be sensed internally. These observations demonstrate that computer tracking is a sensitive method of analyzing animal behavior. It is further demonstrated that a significant response can be detected to a relatively weak stimulus in less than 5 min.     

The glycosylceramides of the nematodeCaenorhabditis elegans contain an unusual,branched-chain sphingoid base

Caenorhabditis elegans was cultured in semi-defined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitosterol. Monoglycosylceramides were chromatographically purified from nematode extracts. Their structures were elucidated with mass spectrometry, nuclear magnetic resonance spectroscopy, and analysis of methanolysis products of the parent cerebrosides. The glycosylceramides were unusual in that the only long-chain sphingoid base detected was aniso-branched compound with a C-4 double bond (i.e., 15-methyl-2-aminohexadec-4-en-1,3-diol). Glucose was the only sugar moiety detected. The fatty acids consisted of a series of primarily straint-chain, saturated, 2-hydroxylated C₂₀–C₂₆ acids; someiso-branched analogs also occurred. The sphingomyelins ofC. elegans were also hydrolyzed, and the sameiso-branched C₁₇ compound was the only sphingoid base detected. This is the first structural analysis of a nematode glycosphingolipid and the first report of an organism in which the long-chain sphingoid bases are entirelyiso-branched. Fatty acids are represented by a binumeric system in which the first number refers to the chain length, and the second number refers to the number of double bonds.     

Effects of growth temperature on the fatty acid composition of the free-living nematodeCaenorhabditis elegans

The effects of growth temperature on the fatty acid compositions of the phosphatidylcholine (PC), phosphatidylethanolamine (PE), and total lipid (TL) fractions of the free-living nematodeCaenorhabditis elegans were investigated. A reduction in growth temperature from 25 to 15°C caused the proportions of eicosapentaenoic acid (20∶5n-3) to increase from 23.6 to 32.5% in the PC, from 7.4 to 10.8% in the PE, and from 12.9 to 19.9% in the TL fractions. Conversely, the levels of dihomo-γ-linolenic acid (20∶3n-6) and arachidonic acid (20∶4n-6) in these phospholipid fractions and the TL fraction both decreased with decreasing growth temperature. Analysis of the positional distribution of fatty acids in the PC fraction revealed that the change in the composition of C₂₀ polyunsaturated fatty acid was obvious in positionsn-2. Lowering the growth temperature induced an increase in the level of the diacyl subclass of PE from 58% at 25°C to 71% at 15°C, with a concomitant decrease in the levels of the alkylacyl and alkenylacyl subclass of PE ofC. elegans. These changes observed in the phospholipids ofC. elegans might be one mechanism for adaptation to low temperature. Lipids 31, 1173–1178 (1996).     

Laser microbeam studies of role of amphid receptors in chemosensory behavior of nematodeCaenorhabditis elegans

Amphid sensilla, historically considered the primary chemosensory structures of nematodes, were found to be necessary for the detection of only one of the six chemical stimuli that were tested. Only the attraction to cAMP was eliminated by damaging the two lateral lips, which bear the amphid sensilla. The inner labial sensilla, one of which occurs on each of the six lips, are probably the primary receptor structures for the other chemical stimuli. Damaging all six lips, which should destroy all anterior chemosensory input, not only eliminted the attraction to sodium and chloride ions, but reversed the nematodes' response to them. Nematodes with all six lips destroyed showed reversal behavior when exposed to these attractants. Nematodes with damage to all six lips appeared to recover much of their normal chemosensory function within 24 hr after treatment.     

Dealkylation of coal-derived oil by hydrogen from methanol decomposition: 1. Dealkylation of ethylbenzene as a model of coal-derived oil

The possibility of dealkylation of ethylbenzene by the hydrogen generated in situ from methanol decomposition was investigated in a continuous reaction apparatus at temperatures of 650–950 °C, residence times of 6–33 s, sample flow rates of 0.4–0.9 g h⁻¹ and ethylbenzene concentrations of 25–100 vol%. The main dealkylation products were benzene, toluene, styrene, methane and ethylene. Small amounts of condensation products were also identified by gas chromatography. The dealkylation of ethylbenzene was significantly promoted by the hydrogen generated from methanol, without any carbon or tar formation. Kinetic analysis was carried out, assuming first-order reaction. The activation energy of the total reaction was 209 kJ mol⁻¹ and the frequency factor was 9.1 × 10⁹s⁻¹.     

Dealkylation of 24-ethylsterols byTetrahymena pyriformis

WhenTetrahymena pyriformis was incubated with sitosterol ([24R]-24-ethylcholest-5-en-3β-ol]) or itstrans-Δ²²-derivative (stigmasterol), the C-24-dealkylated product, cholesta-5,7,trans-22-trien-3β-ol, was obtained in both cases. 24(S)-24-Ethylcholesta-5,7,trans-22-trien-3β-ol also was found to be a metabolite. When sitosterol was the substrate, 24(R)-24-ethylcholesta-5,7-dien-3β-ol was obtained as a third product. Identifications were made by mass spectroscopy, quantitative chromatography, labeling with¹⁴C, and by other means. The dealkylated product (cholestratrienol) represented 30% of the sterols isolable after incubation. The administration of sterols to this organism did not induce sterol biosynthesis, since 2-¹⁴C-mevalonate failed to yield radioactive sterol in the presence of added stigmasterol.     

Dealkylation of Samla coal under Friedel-Crafts condition

Coal is reported to be alkylated by the Friedel-Crafts reactions under mild conditions. However, dealkylation of an Indian (Samla) coal is reported following treatment at ambient temperature and pressure.     

利用膨胀制冷技术脱水脱烃的实验研究

此研究在长庆榆林气田根据膨胀制冷原理,结合其气田低温分离的特点,进行了天然气脱水脱烃的实验研究。长庆榆林气田目前多采用针阀节流的方式达到降压降温的目的,利用低温分离工艺进行天然气脱水、脱烃处理。对于井口压力低的井,采用针阀节流要达到低温分离目的所需的压降较大,达不到外输压力要求。在这种情况下,此研究使用膨胀制冷管开展实验研究,利用系统已有的背压条件取得相应的温度降,促进了气体中的游离水、重烃类的凝析。     

Dealkylation of N,N-dimethylaniline with sulphur and hydrogen sulphide

N,N-Dimethylaniline successively demethylates at 425 °C in the presence of hydrogen and hydrogen sulphide or sulphur to give successively N-methylaniline and aniline. For the dealkylation reaction, the rank order of promotors is S >SH₂ >H₂S >H₂SH₂ >H₂.     

Preparation of14C-gossypol by incorporation of acetate-1-14C and acetate-2-14C by biosynthesis

Details for the germination of cotton seedlings and their utilization for incorporating¹⁴C-labeled acetate into gossypol are presented. Methods for the isolation and purification of the biosynthesized gossypol are given. The specific activity of the gossypol obtained from root tissue and cotyledons had mean values for 8 preparations of 428.6×10³ and 6.3×10³ dpm/mg, respectively. Corresponding incorporations were 5.42 and 0.32%. Paper no. 4190, North Carolina State University Experiment Station, Raleigh, N.C.     

Fe(TSPc)-Catalysed Benzylic Oxidation and Subsequent Dealkylation of a Non-Phenolic Lignin Model

Abstract

The mechanism by which the phthalocyanine complex trisodium tetra-4-sulfonatophthalocyanineiron(JJJ) (Fe(TSPc)) promotes oxidation and dealkylation of non-phenolic benzyl alcohol units in lignin under alkaline conditions was investigated using simple lignin model compounds. The iron complex effectively oxidised benzylic hydroxyl groups in 2-hydroxyethyl apocynol (5), with the extent of oxidation increasing with the amount of Fe(TSPc) added. To a limited extent, Fe(TSPc) also catalysed the oxidation of 5 by small amounts of oxygen in the reaction mixture. However, the extent of oxidation did not increase on adding excess air or oxygen, as greater amounts of oxygen also increased complex degradation. Phenolic products were formed in these reactions in the presence of Fe(TSPc), but at a rate slower than that of the benzylic oxidation. Further experiments indicated that the phenolic products were formed by base-promoted loss of the ether group at C4 and that such dealkylation occurred more readily in oxidised products.     

利用不同碳源合成生物表面活性剂的研究

铜绿假单孢菌在葡萄糖，甘油、石蜡、菜油培养基中合成鼠李糖酯生物表面活性剂的最高产量分别为0．48g/L、18．90g/L、2．28g/L、13．50g/L。根据各碳源的代谢特点和相应的发酵动力学，分析认为葡萄糖和短链烷烃东适合生物表面活性剂的合成，甘油发酵中细胞生长和产物合成沿着相同的代谢途径，细胞的适应性好，鼠李糖酯产量高，从经济性考虑，菜油是大规模生产生物表面活性剂的首选碳源。     

Adsorption of disperse dye by various adsorbents

Laboratory investigations of C.I. Disperse Red 60 adsorption on molecular sieves, activated alumina, granular activated carbon (GAC), diatomite and sawdust were conducted in this study. The effectiveness of those adsorbents for pollutant removal and color reduction of disperse dye was examined and compared with that of powdered activated carbon (PAC). It was found that the activated alumina has only 61% COD removal efficiency in comparison with that of PAC while those of molecular sieves, GAC and diatomite are much lower. In terms of color removal, activated alumina and molecular sieves are as effective as PAC while GAC, diatomite and sawdust are much less effective. The monolayer Langmuir isotherm was found to represent well the measured adsorption data and the constant parameters of the adsorption isotherm were determined for all adsorbents. The simplified mass transfer model proposed previously was also used for estimating the mass transfer coefficients using the initial adsorption data for several adsorbents.     

Uptake of blood triglyceride by various tissues

Triglycerides are transported in the blood in chylomicrons and very low density lipoproteins. Electron microscopic studies indicate that these particles, which range in diameter from 0.03–0.6 μ, cannot cross the capillary endothelium in most tissues. There is now considerable evidence that the triglycerides are hydrolyzed to free fatty acids (FFA) during uptake and that this process is catalyzed by lipoprotein lipase. The enzyme is found in nearly all tissues that utilize circulating triglyceride, and the level of activity, in individual tissues, varies with nutritional and physiological states that affect triglyceride uptake, such as fasting, diabetes and pregnancy. Studies in perfused adipose tissue with doubly labeled chylomicrons showed that hydrolysis occurs outside of the blood stream. Two-thirds of the fatty acids are incorporated into tissue triglyceride and the rest are release as FFA, with glycerol, to the blood. Infusion of heparin causes immediate release of lipoprotein lipase activity to the blood and decreases the amount of chylomicron-triglyceride hydrolyzed by the tissue. Electron microscopic cytochemical studies showed that hydrolysis of blood glycerides by lipoprotein lipase in adipose tissue occurs within the capillary endothelial cells and in the subendothelial space near the pericytes, but not in the capillary lumen or near the fat cells. The results indicate that the fatty acids of chylomicrons cross the capillary endothelium as glycerides and FFA, within a membrane-bounded system, and cross the extravascular space to the fat cells as FFA. Presented at the AOCS Meeting, Atlantic City, October 1971.     

Porosity of polymer materials by various techniques

The porosity of porous copolymer 1-vinyl-2-pyrrolidone-divinylbenzene has been studied by nitrogen adsorption, temperature programmed desorption, and positronium annihilation lifetime spectroscopy. It was shown that the pore structure characteristics depends on the swelling of the polymer material in various solvents. The structural features of polymeric materials restructured under different conditions are described and the structural changes are discussed. The applicability of PALS technique in structural investigations is presented.     

1-14C-Linoleic acid distribution in various tissue lipids of guinea pigs following an oral dose

A recent study on the metabolism of 1-¹⁴C-α-linolenic acid in the guinea pig revealed that the fur had the highest specific activity of all tissues examined, 48 h after dosing. The present study investigated the pattern of tissue lipid labeling following an oral dose of 1-¹⁴C-linoleic acid after the animals had been dosed for the same time as above. Guinea pigs were fed one of two diets with a constant linoleic acid content (18% total fatty acids) and a different content of α-linolenic acid (0.3 or 17.3%) from weaning for 3 wk and 1-¹⁴C-linoleic acid was given orally to each animal for 48 h prior to sacrifice. The most highly labeled tissues (dpm/mg of linoleic acid) were liver, followed by brain, lung and spleen, heart, kidney and adrenal and intestines, in both diet groups. The liver had almost a three-fold higher specific activity than skin and fur which was more extensively labeled than the adipose and carcass. Approximately two-thirds of the label in skin plus fur was found in the fur which, because of a low lipid mass, would indicate that the fur was highly labeled. All tissues derived from animals on the diet with the low α-linolenic acid level were significantly more labeled than the tissues from the animals on the high α-linolenic acid diet, by a factor of 1.5 to 3. The phospholipid fraction was the most highly labeled fraction in the liver, free fatty acids were the most labeled fraction in skin & fur, while triacyglycerols were the most labeled in the carcass and adipose tissue. In these tissues, more than 90% of the radioactivity was found in fatty acids with 2-double bonds in the tissue lipids. These data indicate that the majority of label found in guinea pig tissues 48 h after dosing was still associated with a fatty acid fraction with 2-double bonds, which suggests there was little metabolism of linoleic acid to more highly unsaturated fatty acids in this time frame. In this study, the labeling of guinea pig tissues with linoleic acid, 48 h after dosing, was quite different from the labeling with α-linolenic acid reported previously. The retention of the administered radioactivity from ¹⁴C-linoleic acid in the whole body lipids was 1.6 times higher in the group fed the low α-linolenic acid diet (diet contained a total of 1.8 g PUFA/100 g diet)compared with the group fed the high α-linolenic acid diet (diet contained 3.6 g PUFA/100 g diet). The lack of retention of ¹⁴C-labeled lipids in the whole body would be consistent with an increased rate of β-oxidation of the labeled fatty acid on the diet rich in PUFA, a result supported by other studies using direct measurement of labeled carbon dioxide.     

Catalytic graphitization of carbons by various metals

A study was made of the catalytic graphitization of carbons by 22 kinds of metals. Heat treatments were carried out at 2600°C for 1 hr and 3000°C for 10 min under argon atmosphere. In graphitizing 3,5-dimethylphenol-formaldehyde resin carbon powder with which 20w/o metal powder (Al, Cr, Mn, Fe, Co, Ni, Ca, Ti, V, Mo and W) was mixed, graphitic carbon was catalytically formed. The first six metals, which belong to the carbon dissolution-precipitation mechanism, gave large graphitic crystal flakes at an early stage of the reaction; the other metals resulted in fine crystals through the carbide formation-decomposition mechanism. For the non-graphitizing phenol formaldehyde resin carbon in which 10w/o metal powder was dispersed, Mg, Si, Ca, Cu and Ge catalyzed formation of only graphitic carbon; and Al, Ti, V, Cr, Mn, Fe, Co, Ni, Mo and W formed both graphitic and turbostratic carbons. Except for Al and Cu, the former effect was exerted by non-transition metals and the latter effect by transition metals. Boron alone markedly accelerated homogeneous graphitization of both kinds of carbon; and Zn, Sn, Sb, Pb and Bi had no catalytic effect. On the basis of these results, the relationships between some properties of the metals, their catalytic abilities and the kind of catalytic effects are discussed.